This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are collecting fiber diffraction data from flexible filamentous plant viruses, invaluable as models for recognition, assembly, flexibility, viral-host interactions, and in methods development. Plant viruses have great potential in biotechnology, but development will require three-dimensional structures. Fiber diffraction is often the only method available for the determination of such filamentous structures. Diffraction samples are oriented sols and dried fibers. We find that order is better in dried fibers of highly flexible filaments, and in oriented sols of more rigid filaments. Dried fibers require much less material, an important consideration for studies of low-titer viruses. Wide and small angle diffraction data are collected at BioCAT;wide-angle data are also collected at BioCARS under a joint arrangement between the two beamlines. We collected wide-angle data on the filamentous plant viruses in August 2008. We obtained fiber diffraction data from potato virus Y (family Potyviridae), beet yellows virus (family Closteroviridae), and hibiscus latent Singapore virus (genus Tobamovirus). The HLSV data were particularly noteworthy, being the highest resolution (between 2.4 and 2.0, to be determined more accurately during later analysis) filamentous virus data that we have ever collected.